#imports 
import { Observable, of } from 'rxjs';
import { tap, delay } from 'rxjs/operators';

#service
isUserLoggedIn: boolean = false;

  login(userName: string, password: string) {
     console.log(userName);
     console.log(password);
     this.isUserLoggedIn = userName == 'admin' && password == 'admin';
     localStorage.setItem('isUserLoggedIn', this.isUserLoggedIn ? "true" : "false"); 

  return of(this.isUserLoggedIn).pipe(
     delay(1000),
     tap(val => { 
        console.log("Is User Authentication is successful: " + val); 
     })
  );
  }

  logout(): void {
  this.isUserLoggedIn = false;
     localStorage.removeItem('isUserLoggedIn'); 
  }